Evaluation of the antibacterial activity and toxicity of Myrciaria caulifloria methanolic leaf and fruit extracts

Abstract

Methanol extracts from M. caulifloria leaves and fruit were tested for antimicrobial activity and toxicity in vitro. M. caulifloria leaf extractinhibited the growth of 9 of the 14 bacteria tested (64%) whilst the fruit extract inhibited the growth of 11 of the 14 bacteria tested (79%). Both Gram-positive and Gram-negative bacterial growth were inhibited by M. caulifloria leaf and flower extracts. 7 of the 10 Gram-negative bacteria (70%) and 2 of the 4 Gram-positive bacteria (50%) tested had their growth inhibited by M. caulifloria leaf extract whereas the fruit extract inhibited 7 of the 10 Gram-negative bacteria (70%) and 100% of the Gram-positive bacteria tested. M. caulifloria leaf extract proved to be toxic in the Artemia fransiscana bioassay with 24, 48 and 72h LC50's of 232.9 ᠳ6.3 姯ml, 169.1 ᠱ1.5 姯ml and 128.1 ᠵ.6 姯ml respectively, making it more toxic than Mevinphos (24, 48 and 72h LC50's 1346.0 ᠷ8.2 姯ml, 505.3 ᠳ7.7 姯ml, 103.9 ᠱ2.8) at all time points except 72h but less toxic than potassium dichromate (24, 48 and 72h LC50's 86.3 ᠵ.1 姯ml, 80.4 ᠴ.3 姯ml, 77.9 ᠴ.9). M. caulifloria fruit extract was non-toxic in the Artemia fransiscana bioassay indicating its potential as an antibacterial agent for medicinal use.